One of the major issues that affects progress in mutual Christian understanding is that of the possibility of change - change in theology, in credal formulae, in the institutions of Christianity and in worship. Many Christians emphasize the large unchanging element, all that seems set for ever. Others see very little that is unchanging and therefore feel free to develop new ways of thought,expression and action.In his new book Bernard Thorogood explores this divide. He does not see change as an enemy to be resisted, but as the necessary risk entailed in all faithful pilgrimage. So as he looks at Christian worship, Christian belief, thought and practice he pleads for greater understanding and acceptance of change. It is not that change means progress, but that unchangeability belongs to God and not to any work of human minds and hands.